You may not know that liquid crystal components can be used for more than just displays and can be deployed to control the polarisation of, modulate and control the intensity of light in applications ranging from welding to machine vision, biometrical sensing to videography.
Given their solid-state nature, fast switch rate, accuracy, product lifetime and proven reliability, liquid crystals can have significant advantages over other technologies.
We work with our OEM customers to understand their light control needs. The applications we cater for and the three classes of liquid crystal components we provide are:
- For intensity and polarisation control:
– Fast optical shutters
– Polarisation modulators and rotators - For photography and videography applications:
– Variable Neutral Density filters
Fast Optical Shutters
Fast optical shutter (FOS) devices are based on nematic crystals and offer control of transmission by varying an externally controlled voltage. The shutter is composed of a polarisation modulator made up of either a single, or two liquid crystal cells positioned between two orthogonal linear polarisers. By applying a voltage across the LC cell the LC matrix is reorientated and so the transmittance of light.
Fast optical shutters also allow for grey-scale operation. The fast optical shutter can operate between fully open and fully closed when the applied voltage is varied.
The range we offer comprises:
- FOS – GP shutter for visible wavelengths, wide-view and reduced closed state light leakage at oblique angles.
- FOS(G2) – Second generation shutter similar to FOS, G2 has faster switching times.
- FOS(G2)-CE – Dual-cell contrast enhanced (≥120,000:1) version of FOS(G2).
- X-FOS(G2) – This model offers even faster switching.
- PolarSpeed® – Ultra-fast symmetrical switching FOS.
- FOS-NIR – Broadband visible and NIR (up to 2000nm) FOS with hard coat film on the outer surface.
Polarisation Modulators and Rotators
Liquid crystal Fast Polarisation Modulator (FPM) and Variable Polarisation Rotator (VPR) components have no moving parts, are vibration-free, are very compact.
The orientation of the LC matrix and as a result the polarisation of light is changed when a voltage is applied to the liquid crystal-based polariser.
The choice of product depends on the application:
- FPM(L) – Suitable for customers seeking a general-purpose modulator, this model offers high contrast between polarisation outputs at moderate drive voltage and fast switching.
- FPM(L)-NIR(1100) – Visible and near-infrared operation from 400nm to >2000nm, the standard model is optimised for maximum polarisation contrast at 1,100nm. For OEM applications it is possible to specify the maximum wavelength.
- X-FPML – The best model for high-frequency operation and the fastest single-cell modulator with extra-fast switching speeds.
- X-FPM(4L) – For polarisation imaging this model employs a dual-cell structure in order to achieve switching between four linear polarisation states through 135°.
- PolarSpeed®-M(L) – The PolarSpeed® modulator is especially suitable for demanding high frame rate applications, such as time-multiplexed stereoscopic 3D and is compatible with up to 540FPS operation. This dual-cell modulator offers unprecedented 30µs symmetrical switching times in both directions.
- VPR (Variable Polarisation Rotator) – The VPR differs from all other polarisation modulator models by offering continuous analogue rotation of linear polarisation output states between 0° and 180°.
All FOS, FPM and VPR models feature an anti-reflective (AR) coating to minimise surface reflection. For mono imaging applications requiring minimum wavefront distortion we recommend the “IQ” variants which feature optically flat cover slides with high performance AR-coating.
Variable Neutral Density Filters (vNDF)
Our vNDF models are optimised for full colour imaging applications with a flat transmission curve across visible wavelengths together with low off-axis transmission loss and colour shift. By controlling the amount of light entering the camera, the user is able to work with variables such as aperture, exposure time and sensor sensitivity and without concern for overexposure.
The new PolarView®-eND (electronic neutral density) filter is the first front-mounted electronic neutral density filter that offers accurate, continuously adjustable neutral density filtration over a 1.5-5, or 2-7 stop range. It is designed to work in a conventional matte box or lens adapter mount and has negligible vignetting across the frame. The PolarView®-eND is also compatible with fixed type internal ND filters on cameras like the ARRI Alexa Mini LF and Sony Venice 2.
The PolarView®-eND represents a significant development for cameras. By positioning the filter in front of rather than behind the lens, density strengths, vignette, flare, and dust are not magnified and so the image is not contaminated. It offers camera users a new level of control over their images, without the need to change filters during use. This can save time and improve the overall quality of the image.
Additional details:
- Available in matte box-sized and lens adapter-sized versions.
- Designed to match full frame SLR image sensors with an outline of 44.0 x 33.6mm² and a 30 x 26.0mm² switching area.
- Custom sizes possible, including 40 x 30mm² and 2" x 2".
- Can be used cameras such as the ARRI Alexa Mini LF, Sony Venice 2, RED VV and Panavision DXL2.
- It has a battery life of up to 10 hours.
- Made in Sweden.
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If you’d like to discuss your application and liquid crystal component needs, contact Martin at AP Technologies
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